Mr Singh, a known detractor of Mr Modi, also dismissed his talk of inclusive politics, wondering whether a leopard can "change its spots".
Soon after Mr Modi, while addressing his NRI supporters via a video conference, launched a full scale attack on UPA, the AICC general secretary trained his guns on the BJP's prime ministerial candidate through the community microblogging site Twitter seeking to dismiss his criticism and alleging that Mr Modi was giving "fake figures" of growth during the NDA regime.
"Good to hear Modi talking about Inclusive Politics. But can a leopard change its spots ? FEKU MODI at his best.Giving fake figures of growth during NDA regime," Mr Singh tweeted.
Mr Singh also seemed to be addressing the electorate, telling them, "Congress empowers YOU// Modi empowers HIMSELF! Choice is yours! Modi wants CONGRESS MUKT BHARAT AND WE WANT BHOOK MUKT BHARAT ! He backs PRIVILEGED Congress backs UNDERPRIVILEGED.Choice is yours !"
As Mr Modi slammed the UPA government over various issues including slow growth rate, the Congress general secretary retorted that the UPA had fulfilled every promise made by giving Rights on Information, Education, Food Security and Rights to women and tribals and also the Right to Work.
"The list can go on. Would Modi have courage to debate with one of us on issues of governance, development and other National Issues?," he said.
Alluding to post-Godhara riots in Gujarat, corruption issues in some BJP-ruled states and cash on camera scandal involving a former BJP President in the past, Mr Singh ridiculed Mr Modi's claim that people were looking at the BJP to bring a positive change in the nation and wondered whether it will be "because thousands were killed in communal riots. Because rules were bent to favour the favourites! Because of Bangaru Laxman caught on camera".
The Congress leader was also acerbic in his criticism of the Gujarat Chief Minister over his praise of Atal Bihari Vajpayee. "Modi- "Atalji's was a Golden Era"// Because Modi didn't follow Raj Dharm? Parliament was attacked by Terrorists?Terrorists were released?," Mr Singh tweeted.
Praising the six-year tenure of NDA under the leadership of Mr Vajpayee, Mr Modi said, "Under Vajpayee government it looked like that the 21st century would be the century of India. But with his departure, the downfall started".